The present invention relates to a drive system for a drying apparatus and more particularly to a drive system for a compact rotary drum type drying apparatus.
It is already known from prior art patents relating to drying apparatus that a drive system having a radial air-gap induction motor is provided in an outer case of the drying apparatus for driving a rotary drum through a pulley and drive combination.
For example, U.S. Pat. No. 2,925,665 discloses a rotary drum type drying apparatus having a drive system which comprises a radial air-gap induction motor located on the bottom of the outer case and for driving the rotary drum as well as a blower through pulleys and drive belts which form a two stage speed reduction mechanism for speed variation from the 1500-1800 r.p.m. range of the motor to the 40-50 r.p.m. range to suitably drive the rotary-drum with the maximum efficiency. However, such a drive system should include a complicated drive pulley and belt mechanism having the two stage speed reduction.
Further, U.S. Pat. No. 3,471,940 discloses a drying apparatus including a drive system which comprises a drive pulley of a small diameter fitted onto the shaft of a radial air-gap induction motor. This drive pulley cooperates with a drive belt running around the outer periphery of a rotary drum so as to rotate the latter with the maximum efficiency. Since the diameter of the drive pulley is extremely less than that of the rotary-drum, an idler pulley is inevitably provided for tensioning the drive belt so as to prevent the drive pulley from being slipping on the drive belt.
Further, these prior art drive systems should have a bearing unit mounting a blower fan and another pulley and belt mechanism for driving the blower fan. Further, in these prior art drive systems, the drive motor should be mounted on the bottom of the outer case with a some clearance between the rotary drum and the drive motor in order to avoid the interference with the rotary drum rotating, which inevitably increases the dimension of the outer case with having a large dead space, causing an increase in the height of the outer case. Therefore, the access opening of the drying apparatus must be positioned at a relatively high level. It presents a problem when the drying apparatus is arranged above a washing apparatus, since, in such a case, accessibility of fabrics to be dryed becomes worse.